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The Thermal Noise Interferometer Measuring Displacement Noise in Advanced Suspended Interferometers. Ken Libbrecht, Eric Black, Luca Matone, Shanti Rao LIGO/Caltech. Objectives: Characterize Advanced Detectors Verify Design Specifications Measure Noise Sources
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The Thermal Noise Interferometer Measuring Displacement Noise in Advanced Suspended Interferometers Ken Libbrecht, Eric Black, Luca Matone, Shanti Rao LIGO/Caltech Objectives: Characterize Advanced Detectors Verify Design Specifications Measure Noise Sources Measure Non-thermal Noise Properties Physics of Fundamental Noise Sources Noise Physics, Statistics Reach (and Exceed) the SQL LIGO-G000268-00-D
TNI Design Elements The many advantages of using a short cavity length (L 1cm) Short Cavity Storage Time Use High Finesse Cavities No Power Recycling Independent Cavities No Recombination Independent Controls Reduced Optical Pointing Requirements - no WFS Reduced Laser Stability Requirements Common Support for Test Masses Reduced Seismic Noise Lower Suspension Recoil Thermal Noise But…Smaller laser spot size Higher Internal Thermal Noise
TNI Initial Layout • Phase I: • Steel Wire Suspensions • Modified LIGO SOS • 4x4 inch Test Masses, Corning 7980, F = 100,000 • L = 1 cm; 0.15 mm spot size • OSEM mirror sensor/drivers LIGO PSL copy
TNI New Layout Common mode rejection used to separate laser frequency noise
TNI Outside View …before clean-room cover around vacuum chamber
The TNI crew Eric Black Luca Matone Seiji Kawamura Shanti Rao
TNI Phase I Expected Spectrum 1st spectrum: 12/2000
TNI Phase II Expected Spectrum Sapphire Test Masses Magnetic Controls Wire Suspensions
PhotoThermal Noise Measurement Modulate Intensity of Pump Beam Monitor Cavity Response using Probe Beam
SAS/ITNI SAS/TAMA ITNI TNI-I TNI-II Univ. Tokyo Kimio Tsubono Kenji Numata +grad student LIGO/Caltech Univ. Firenze and Urbino Flavio Vetrano Ruggero Stanga Giovanni Losurdo Ken Libbrecht Eric Black Luca Matone Shanti Rao Phil Willems Ron Drever Eugene Cowan Riccardo DeSalvo Virginio Sannibale Akitero Takamori Joseph Kovalik Szabolcs Marka Alessandro Bertolini Flavio Nocera Univ Pisa Francesco Fidecaro Niccolo Beverini Giancarlo Cella +grad student Nat. Astr. Obs. Japan Seiji Kawamura The International Thermal Noise Interferometer (ITNI) Principal Objective: Examine Fused Silica Suspension Noise Pendulum Thermal Noise not yet measured Non-Gaussian events probably dominate data analysis Physics not well understood Determine optimal stress in fibers Experiment Upgrade: Push to Lower Frequencies Combine SAS and TNI, plus collaborators time
ITNI with “LIGO-like” F.S. test masses Common mode rejection used to separate seismic suspension noise from F.S. suspension noise